With rapid development of electronic and information industries, computers and the peripheral device thereof become essential parts in our daily lives. For example, mice are important peripheral devices of computers for establishing contact between the personal computers and the users. For helping the user well operate the computer, many novel mice with expanded functions are developed in views of humanization and user-friendliness.
For facilitating the user to browse web pages or documents containing a great amount of data, a wheel mouse having an additional wheel has been developed to perform a vertical scrolling function. By rotating the wheel of the wheel mouse forwardly or backwardly, the graphic-based window or the web page shown on the computer screen may be scrolled in the vertical direction. FIG. 1 is a schematic side view of a conventional wheel mouse. As shown in FIG. 1, the conventional wheel mouse 1 principally comprises a mouse case 10, a wheel 11 and an encoder 12. A portion of the wheel 11 is protruded out of the mouse case 10 such that the wheel 11 can be rotated by a user's finger. In addition, the wheel 11 is sheathed around the rotating shaft 13. An end of the rotating shaft 13 is inserted into the encoder 12. Upon rotation of the wheel 11, the encoder 12 generates an electronic signal. In response to the electronic signal, a vertical scrolling function of the wheel mouse 1 is executed, and thus the graphic-based window or the web page shown on the computer screen is scrolled in the vertical direction.
Recently, the trend of designing a mouse is toward a slim type mouse in order to enhance its portability. For reducing the thickness of the wheel mouse, the height of the mouse case 10 needs to be as small as possible. For reducing the height of the mouse case 10, the heights or the volumes of individual components within the mouse case 10 needs to be reduced. Among the internal components of the mouse case 10, the wheel 11 and the encoder 12 are relatively higher. For reducing the height of the mouse case 10, there are two important issues required to be taken into consideration. Firstly, the wheel 11 needs to be partially protruded out of the mouse case 10. Secondly, the rotating shaft 13 needs to be inserted into the encoder 12. In a case that the location of the wheel 11 is lowered or the diameter of the wheel 11 is reduced, the wheel 11 is usually exposed outside of the mouse case 10 or the rotating shaft 13 is difficult to be inserted into the encoder 12. Under this circumstance, the function of the wheel 11 fails to be successfully executed. In another case that the volume of the encoder 12 is reduced or the location of the encoder 12 is lowered, the location of the wheel 11 may be slightly lowered. Since the wheel 11 needs to be partially protruded out of the mouse case 10 and the rotating shaft 13 needs to be inserted into the encoder 12, the diameter of the wheel 11 cannot be reduced. In other words, the extent of reducing the height of the mouse case 10 according to the prior art is still not satisfied.
Recently, wider computer screens are gradually adopted. For scrolling the graphic-based window or the web page shown on the computer screen in the horizontal direction, a so-called tilt wheel mouse has been developed to perform the horizontal scrolling function. Therefore, there is a need of providing a wheel mouse having the functions of a slim wheel mouse and a tilt wheel mouse.